title: Smooth muscle cell migration and proliferation are mediated by distinct phases of activation of the intracellular messenger mitogen-activated protein kinase.
abstract: OBJECTIVE
  Mitogen-activated protein kinase (MAPK) is a ubiquitous signaling protein that has been associated with cellular proliferation; however, its role in cellular migration has not been established. In this study, we investigate the role of MAPK in platelet-derived growth factor (PDGF)-induced migration and proliferation of human vascular smooth muscle cells (SMCs).
  
  
  METHODS
  SMC migration was measured using a microchemotaxis assay (4 hours), and proliferation was assessed using 3H-thymidine uptake and cell counts. PD098059 was used as a specific noncompetitive inhibitor of MAPK activation.
  
  
  RESULTS
  Coincubation of SMCs with PD098059 resulted in significant inhibition of PDGF-BB (5 ng/ml)-induced SMC chemotaxis and proliferation. The IC50 for both processes was approximately 10 mumol/L with complete inhibition at 50 mumol/L. Stimulation of SMCs with PDGF produced an early peak in MAPK activity followed by a plateau of activity that persisted for 24 hours. We hypothesized that variations in the temporal activation of MAPK might explain the action of this enzyme on these two disparate cellular events. By adding PD098059 at intervals after stimulation of SMCs with PDGF, we demonstrated an association between MAPK activity within the first 15 minutes and SMC migration, whereas MAPK activity between 1 and 4 hours was associated with SMC proliferation.
  
  
  CONCLUSIONS
  MAPK activity is essential for both SMC migration and proliferation, and distinct phases of enzyme activation are required to stimulate these two discrete cellular events. Inhibition of this signaling protein may prove to be a useful method for preventing intimal hyperplasia.
authors.affiliation: Department of Surgery, Beth Israel/Deaconess Medical Center, Harvard Medical School, New York, NY, USA.
authors.forename: P R
authors.initials: PR
authors.lastname: Nelson
authors.forename: S
authors.initials: S
authors.lastname: Yamamura
authors.forename: L
authors.initials: L
authors.lastname: Mureebe
authors.forename: H
authors.initials: H
authors.lastname: Itoh
authors.forename: K C
authors.initials: KC
authors.lastname: Kent
mesh_terms: D000077214:Becaplermin; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion; D002452:Cell Count; D002455:Cell Division; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D002633:Chemotaxis; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000502:physiology; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins
chemical_list: D005419:Flavonoids; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D000077214:Becaplermin; D004247:DNA; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one